NUCLEO-H7S3L8 SPI Transmission Issue - TXDR Register Not Updating

[aditya_prajapati]

Hello,

I'm working with the NUCLEO-H7S3L8 microcontroller and trying to transmit data using SPI, but I'm encountering an issue where the TXDR (Transmit Data Register) is not updating.

I have generated the code using STM32CubeIDE Version: 1.17.0 and SDK version STM32Cube_FW_H7RS_V1.1.0, keeping most of the settings default.

SPI Configuration (via STM32CubeIDE GUI):

• Configured SPI in full-duplex master mode.
• Set data size to 8-bit.
• Adjusted the prescaler for 75 Mbit/s (currently, speed does not seem to affect the issue).
• Connected the MISO pin to the MOSI pin (PA6 <---> PB5) using a jumper. (Loopback Test)

Issue:

• SPI communication does not seem to initiate.

Debugging Observations:

• Execution gets stuck in the HAL_SPI_TransmitReceive function when using the HAL_MAX_DELAY macro.
• TXDR register remains unchanged when writing data.

Questions:

1. Why is the TXDR register not updating when writing data?
2. Are there any specific settings required for the SPI peripheral in the NUCLEO-H7S3L8 series?
3. Could this be related to clock configuration or a missing initialization step?
4. Is there a required sequence for enabling SPI transmission that I might be missing?

I would appreciate any insights or suggestions. Thanks in advance!

[Andrew Neil]

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@aditya_prajapati wrote:

• TXDR register remains unchanged when writing data.

Questions:

1. Why is the TXDR register not updating when writing data?

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Beware that hardware registers are not just memory - is there any reason to believe that you should be able to read-back what you wrote to it ?

https://community.st.com/t5/stm32cubeide-mcus/best-technique-for-viewing-uart-debugging-is-dr-register/m-p/768141/highlight/true#M33976

[aditya_prajapati]

Yes, I understand that, but the main issue remains the same. SPI is working even when it is not in debug mode. Do you have any other suggestions as to why it’s not working? I was just trying to debug and understand why SPI is not functioning properly.

[aditya_prajapati]

Apologies for miss typing. It's

"SPI is not working even when it is not in debug mode. Do you have any other suggestions as to why it’s not working?"